i.MX6 SSI PLL frequency question

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i.MX6 SSI PLL frequency question

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uolli
Contributor III

Hi All,

I am checking the datasheet of i.MX6 for the SSI interface, i saw there is a PLL freq 688.128MHZ shows in the table 64-6 as following picture, i am wondering how they got that frequency?

q1.JPG.jpg

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AnsonHuang
NXP Employee
NXP Employee

Hi, uolli

     I saw audio PLL from CCM, I think its freq is set like this: PLL output frequency = Fref * (DIV_SELECT + NUM/DENOM), there are NUM and DENOM can be set to different value, so I think it is possible to get 688.128MHz. such as , DIV_SELECT = 28, NUM = 672, DENOM = 1000, then PLL output will be 24MHz * 28.672 = 688.128MHz. And SSI can be sourced from audio PLL.

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dabrain
Contributor I

How do you source ssi from PLL?

I would like to have a ssi sys clk set to 12.288 or 11.2896 in order to get my different sample rate but i dont find how to do this in imx_ssi.c or anywhere else ...

Best regards.

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AnsonHuang
NXP Employee
NXP Employee

Hi, uolli

     I saw audio PLL from CCM, I think its freq is set like this: PLL output frequency = Fref * (DIV_SELECT + NUM/DENOM), there are NUM and DENOM can be set to different value, so I think it is possible to get 688.128MHz. such as , DIV_SELECT = 28, NUM = 672, DENOM = 1000, then PLL output will be 24MHz * 28.672 = 688.128MHz. And SSI can be sourced from audio PLL.

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uolli
Contributor III

Thank you, Yongcai.

Also, does the freescale has some documents for the SSI how to set as a network mode, i want set SSI working in network mode, with 2.048MHZ T/R clock, with 8K sync clock. also, i checked the source codes for BSP for support codec wm8962, they used SSI 1 for AUDMUX, internal port of AUDMUX is 2, external port is 4, i can saw how to configure the AUDMUX for port2 and 4, but i don't how the SSI 1 to connect to AUDMUX internal port 2. thank you

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AnsonHuang
NXP Employee
NXP Employee

HI,uolli

   Sorry, I am not familiar with SSI module, I am just familiar with PLL and clock, you may need to create another topic for SSI, hope there will be someone helping you.

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uolli
Contributor III

Thank you, Yongcai.

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